Kelly foot valve

ABSTRACT

A valve assembly to be disposed between lower end of kelly and upper end of drill string comprises a spring loaded upwardly closing, pressure release, poppet valve, the poppet including an upwardly opening check valve with a frangible closure for the passage of well tools. A foraminous skirt on the downstream side of the poppet provides a strainer for the drilling fluid. An annular flange carried by the skirt engages and seals with the inside of the valve housing to provide increased area subject to upstream pressure when the poppet opens, the housing being ported to atmosphere downstream of the flange and the skirt sealing with the housing below the port to prevent loss of drilling fluid. The spring is housed in the annulus formed between the skirt and housing.

United States Patent Garrett 451 Oct. 17, 1972 [54] KELLY FOOT VALVE 7 2,675,021 4/1954 Allin ..l37/536 [72] Inventor: William R. Garrett, Midland, Tex. Primary Examiner M y Nelson [73] Assignee: Smith International, Inc., Midland, A i ta tEx i r- Ri hardG a -d Tex. Attorney-Murray Robinson, Ned L. Conley, Robert 22] Filed: July 29 1970 W. B. Dickerson and Bill B. Berrylnll [21] Appl. No.: 58,824 [57] ABSTRACT I v A valve assembly to be disposed between lower end of [52] US. Cl. ..137/71, 137/493.1, 137/536, kelly and upper end of drill string comprises a spring 9 137/544, 166/224 loaded upwardly closing, pressure release, poppet 51 Int. Cl. ..F16k 17/18, F16k 17 40 valve, p pp including an p y p g [58] Field of Search 4 25; 137 3 7 4 9 check valve with a frangible closure for the passage of SIS-515.7, 540

[5 6] References Cited UNITED STATES PATENTS 3,331,385 7/1967 Taylor ..166/224 X 1,873,735 8/1932 Bowman et a1. .......137/7l 2,731,981 l/1956 Glasser 137/536 21,535 9/1858 Hardy et a1 ..137/493.2 2,161,642 6/1939 Stroup ..137/493.6 X

well tools. A foraminous skirt on the downstream side of the poppet provides a strainer for the drilling fluid. An annular flange carried by the skirt engages and seals with the inside of the valve housing to provide increased area subject to upstream pressure when the poppet opens, the housing being ported to atmosphere downstream of the flange and the skirt sealing with the housing below the port to prevent loss of drilling fluid. The spring is housed in the annulus formed between the skirt and housing.

16 Claims, 3 Drawing Figures A \JUU I xkg OOOO COO 0000 000 OOOO COO @000 000 cooo COG KELLY FOOT VALVE CROSS-REFERENCE To Related Applications This application is the parent of a continuation application of the same title Ser. No. 147,484, filed May 27, 1971 by the same applicant as for the present application. The assignee of the present application and said application Ser. No. 147,484 is also the assignee of applications Ser. No. 58,825 filed July 29, 1970 and Ser. No. 147,964 filed May 28, 1971, both directed to subject matter related to that of the present application. The latter applications represent a prior conception upon which the present invention is an improvement.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention pertains to valves and more particularly toa valve assembly of the type known as a kelly foot valve used in the rotary system of drilling oil wells.

Brief Description of the Prior Art A gravity opened, stinger closed kelly foot valve is shown in U. S. Pat. No. 3,191,905 to Brown. This construction isnot adapted to pass instruments and tools therethrough where required.

A full opening flapper gate type spring loaded pressure release, kelly foot valve is shown in US. Pat. No. 3,289,691 to Kennard. However flapper gate valves may not seal tightly.

A spring load poppet type pressure release kelly foot valve is shown in US. Pat. No. 3,331,385 to Taylor. To allow for the passage of tools the poppet includes a removable screw plug. However the tool required for removing the plug may not always be available.

A later U. S. Pat. No. 3,433,252 to Kennard shows a kelly foot valve of the pressure and spring actuated rotary plug type. This valve may be rather expensive to manufacture.

It has heretofore been proposed to incorporate in the seat of a poppet type kelly foot valve such as that shown by Taylor an upwardly opening ball check valve to pass fluid pressure upwardly past the poppet valve at all times to show the existence of such pressure prior to breaking the connection between the kelly and drill pipe whereby the pressure can be relieved before the connection is broken. The combination of an upwardly opening ball check valve in the seat of a downwardly opening spring loaded poppet type pressure release valve is shown in U. S. Pat. No. 2,749,992 to Hill. The proposed kelly foot valve incorporating a Hill type valve construction to indicate the presence of drill string pressure does not provide any means for passing instruments or tools through the valve, possibly because the presence of the ball check valve in the seat restricts the diameter of the poppet.

Various means have been used to keep a spring loaded, kelly foot valve open without the necessity of a pressure drop across the valve equal to the force exertedby the bias spring. In the aforementioned proposed kelly foot valve incorporating the Hill type upwardly opening ball check valve in the seat of the downwardly opening spring loaded poppet, it is proposed to seal off the underside of the poppet from downstream pressure by allowing the underside of the poppet to reciprocate in a cylinder sealed off from the flow passage. In the Kennard rotary, ball plug, kelly foot valve construction, it is not pressure differential across the valve closure that compresses the bias spring; instead an annular piston is geared to the ball and the upper piston head is exposed to upstream pressure and the lower piston head is sealed off from the fluid passage. In the Kennard flapper gate kelly foot valve construction shown in his earlier patent a similar annular piston drive isused, the piston being exposed to upstreampressure on one side and to the pressure in a sealed chamber on the other side. Such arrangements rely on the effectiveness of sliding seals to prevent entrance of upstream pressure into the sealed chamber; if the sealed chamber fills with mud the valve becomes inoperative, remaining in the closed position permanently.

Alternative to the sealed chamber, the Taylor poppet type kelly foot valve, and an alternative flapper gate type kelly foot valve shown in the later Kennard patent, make use of the principle of enlarging the valve opening area exposed to fluid pressure when the valve opens. This is the same principle used in steam safety valves. However in contrast to safety valves, which vent to atmosphere, the additional areas exposed to line pressure when the Taylor and Kennard valves open must rely for their effectiveness upon the dynamic pressure differential between the upstream and downstream sides of the added areas.

SUMMARY OF THE INVENTION According to the invention the difficulties in the aforementioned prior art and proposed constructions are eliminated by providing a kelly foot valve assembly including a downwardly opening spring loaded poppet valve with an upwardly opening, frangible closure, check valve in the poppet, whereby when it is desired to lower instruments or tools through the assembly the frangible check valve closure can be broken out with a conventional wire line sinker bar, always readily available, leaving a substantially full opening through the assembly. A foraminous skirt carried by the poppet on its lower side is spaced from the inner periphery of the valve body downstream from the poppet and slidably seals at its lower end with the inner periphery of a smaller diameter portion of the valve body, whereby fluid passing the poppet is strained by the foraminous skirt before passing into the outlet at the lower end of the valve assembly. The skirt carries an annular flange which seals with the inner periphery of the valve body below the poppet and provides additional area subject to line pressure when the valve opens, the opposite side of the flange being exposed to atmospheric pressure by a vent through the valve body between the skirt seal and the flange seal. The flange also provides a stop against which bears one end of the bias spring, the spring being disposed inside the valve body around the skirt and bearing at its other end against the shoulder formed between the larger and smaller inner diameter portions of the valve body.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1, 2 and 3 of the drawings together form a half section through a kelly foot valve embodying the invention, the three figures showing respectively the top middle and bottom thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT 1 Referring to the drawings there is shown a kelly foot valve assembly comprising an upper sub 10, same being a short length of pipe having a fluid passage 11 therethrough and a threaded box 12 at its upper end for making connection with the lower end of a kelly. The lower end of sub is provided with a threaded pin 13 adapted for making connection with threaded box at the upper end of the tubular valve body 21. The lower end of the valve body is provided with a threaded box 22 for making connection with threaded pin 30 at the upper end ofa lower sub 31. The lower end of sub 31 is provided with a threaded pin 32 adapted to make connection with the threaded box at the upper end of a string of drill pipe. There is a fluid passage33 through lower sub 31 from one end to the other.

Each of the pins and boxes heretofore described is provided with sealing and torque transmitting shoulders as shown at 34, 35, 36, 37, 38, 39 whereby fluid tight connections are provided between the kelly, the upper sub, valve body, lower sub and drill pipe in the ususal manner of rotary shouldered connections.

The pin 13 at the lower end of the upper sub is provided at its lower end with a downwardly flaring conical seat 40. A poppet 41 has a seating surface 42 correlative to seat 40. A tubular skirt 43 depends from the lower end of poppet 41. There is an annular space 44 between the outer periphery of the skirt and the inner periphery of the valve body below seat 40 providing a fluid passage downstream of valve 41 from the fluid passage 11 in upper sub 12 thereabove. When the poppet 41 moves down away from seat 40, opening the valve, fluid can flow from fluid passage 11 into fluid passage 44.

Skirt 43 is slotted at one or more, e.g., four locations around its circumference providing port means 45 for admitting fluid from the annular fluid passage 44 in the valve body into the fluid passage 47 provided by the interior of skirt 43. Fluid passage 47 communicates with fluid passage 33 in the lower sub. An annular lip seal 48 of elastomeric material provides a sliding seal between skirt 43 and pin 30 as the skirt moves down and up during opening and closing of the poppet valve.

A forminous steel sleeve 50 is disposed over the slotted portion of the skirt, being received in reduced diameter section 51 and secured in place by screws 52. The sleeve provides a strainer for mud or other drilling fluid going through the assembly.

An annular flange 60 around skirt 43 is slidable in annular space 44 and carries an annular lip seal 61 of elastomeric material adapted to make a sliding seal with the inner periphery of valve body 21 as the poppet valve moves up and down between open and closed position. A helical spring 62 in the portion of annular space 44 below flange and above the upper end 63 of pin 30 and bearing against said flange and pin end with a predetermined force due to initial compression tends to hold the poppet 41 closed against seat 40. When the valve opens, e.g., due to upstream pressure exerting a force on the poppet in excess of that of the spring, the upstream fluid pressure is admitted to the space 44 above flange 60 and adds to the downward force tending to open the valve. This counteracts the effect of upstream pressure being admitted to the underside of the poppet inside the skirt and at the lower end of the skirt when the valve opens. Therefore the valve opens fully once it begins to open, analogous to a safety valve used on a steam boiler. A port 65 in the wall of the valve body communicates annular space 44 below the flange 60 with atmosphere so that fluid leaking past flange 60 will not disable the valve.

The poppet 41 is annular, providing a flow passage therethrough around the upper end of which is an upwardly flaring, conical seat 71. A closure 72 includes a ring 73 having a conical seating surface 74 correlative to seat 71. An O-ring 67 in seating surface 74 insures a seal with the seat 71. A laminated rubber-aluminumrubber conical cap 75 completes the valve closure. The cap includes an inner core 76 made of brittle aluminum and outer thin rubber layers 77, 78 bonded to the core. The lower end of the cap is provided with threads 79 in the rubber layer 77 which engage threads 80 in ring 73. The closure 72 and seat 71 provide an upwardly opening check valve. To limit upward opening of the check valve closure and to guide the upward and downward movement of the valve closure the closure ring 73 is provided with a downwardly extending skirt 90. The skirt is vertically slotted at 91 for cooperation with a pin 92 screwed into skirt 43.

In operation, during normal drilling the mud pumps will create enough mud pressure in the kelly to open the poppet valve 4140 against the force of spring 62 and the mud will then flow into space 44 and act on flange 60 to hold the valve open. When it is desired to add a length of drill pipe the mud pumps are shut down. If there is still drill string pressure it will open the check valve 72-71 in the poppet 41 and be transmitted through the kelly to the mud pressure gage which will warn the operator to open the bleed off valve until the fluid pressure has dropped to a safe level. The lower sub 31 is then disconnected from the drill pipe. The check valve 72-71 closes under gravity and the hydrostatic pressure of the mud column in the kelly, thereby closing the passage 70 through the poppet 41. The spring 62 exerts enough force to hold the poppet against its seat 40 despite the hydrostatic pressure of the mud column in the kelly. Therefore mud is retained in the kelly rather than being spilled on the rig floor and the operators. It is therefore apparent that a very efficient and safe automatic mud saver valve assembly has been provided. Whenever it is desired to lower an instrument or tool through the assembly, the cap 75 can easily be broken out by lowering a sinker bar through the kelly on a wire line and dropping it through the cap. The parts of the cap are all made of easily drillable material so that no problem results; furthermore the material is light and will float out with the cuttings in the mud. A new cap 75 can easily be screwed in to replace the one broken out. The cap is very inexpensive.

The kelly foot valve assembly just described is preferably made of steel except for the elastomer seals and the frangible closure.

While a preferred embodiment of the invention has been shown and described, modifications can be made by one skilled in the art without departing from the spirit of the invention.

I claim:

1. A kelly foot valve assembly comprising a tubular valve body, a downwardly facing annular valve seat around the interior of the valve body defining a first flow passage, a poppet adapted to engage said seat from the lower side thereof and close said passage, resilient means urging said poppet against said seat, said poppet having a secondflow passage therethrough, an upwardly facing seat around the second flow passage, and a closure engageable with said upwardly facing seat and said closure forming an upwardly opening check valve controlling flow through said fluid passage through said poppet, said poppet and said downwardly facing seat and said resilient means providing a downwardly opening spring loaded poppet valve controlling fluid flow through said first passage, means limiting the upward travel of said check valve closure away from said upwardly facing seat, said check valve closure when away from said upwardly facing seat in the poppet to the limit of upward travel of said check valve closure being out of contact and uncooperative with any other means to limit flow through said assembly, said closure including a central portion that is frangible, the space in said assembly inside said tubular valve body above said closure being clear of ob structions to the passage of tools, whereby a bar can be lowered from above into contact with said. central portion to break it out and upon breaking out of said central portion of the closure there is left a clear path for tools through said flow passage through said poppet, said closure including a steel ring into which is screwed a frangible member adapted to be replaced when broken out, said frangible member being cone shaped, flaring downwardly, whereby the strength of said cone is increased with respect to resistance to fluid pressure from above allowing the frangible member to be made of thin material to facilitate breakout, and whereby fluid flow past said closure when said poppet is open is less turbulent.

2. Assembly according to claim 1 wherein said frangible member comprises a thin laminate including an inner core of brittle aluminum.

3. A kelly foot valve assembly comprising a tubular valve body, a downwardly facing annular valve seat around the interior of the valve body defining a first flow passage, a poppet adapted to engage said seat from the lower side thereof and close said passage, resilient means urging said poppet against said seat, said poppet having a second flow passage therethrough, an upwardly facing seat around the second flow passage, and a closure engageable with said upwardly facing seat from the upper side thereof, said upwardly facing seat and said closure forming an upwardly opening check valve controlling flow through said fluid passage through said poppet, said poppet and said downwardly facing seat and said resilient means providing a downwardly opening spring loaded poppet valve controlling fluid flow through said first passage, and means limiting the upward travel of said check valve closure away from said upwardly facing seat, said check valve closure when away from said upwardly facing seat in the poppet to the limit of upward travel of said check valve closure being out of contact and uncooperative with any other means to limit flow through said assembly, said closure including a central portion that is frangible, the space in said assembly inside said tubular valve body above said closure being clear of obstructions to the passage of tools, whereby a bar can be lowered from above into contact with said central portion to break it out and upon breaking out of said central portion of the closure there is: left a clear path for tools through said flow passage through said poppet, including means around the inner periphery of the valve body below said seat providing an annular seal surface of smaller diameter than said inner periphery of the valve body, and a tubular skirt depending from said poppet and extending to said seal surface when said poppet is in sealing engagement with said seat, and slidable therein in sealing engagement therewith when said poppet moves down away from said seat, the outer periphery of said skirt being spaced radially inwardly from said inner periphery of the valve body leaving an annular space therebetween providing a third fluid passage communicating with said first fluid passage when the poppet is off its said seat, and port means in said skirt communicating the fluid passage provided by said annular space with a fourth fluid passage defined by the interior of said tubular skirt, the inner diameter of said tubular skirt being as large as the outer diameter of said frangible central portion of the check valve closure whereby all tools that will] pass through the remainder of said check valve after said central portion is broken out can pass downwardly through said fourth passage.

4. A kelly foot valve assembly comprising a tubular valve body, a downwardly facing annular valve seat around the interior of the valve body defining a first flow passage, a poppet adapted to engage said seat from the lower side thereof and close said passage, resilient means urging said poppet against said seat, said poppet having a second flow passage therethrough, an upwardly facing seat around the second flow passage, and a closure engageable with said upwardly facing seat from the upper side thereof, said upwardly facing seat and said closureforming an upwardly opening check valve controlling flow through said fluid passage through said poppet, said poppet and said downwardly facing seat and said resilient means providing a downwardly opening spring loadedpoppet valve controlling fluid flow through said first passage, said closure including a steel ring into which is screwed a frangible member adapted to be replaced when broken out, said frangible member comprising an inner core of brittle aluminum and an outer layer of rubber carrying threads for engagement with said closure.

5. Assembly according to claim 4 wherein said frangible member also includes a rubber inner layer.

6. Assembly according to claim 5 wherein said closure is cone shaped, flaring downwardly.

7. A kelly foot valve assembly comprising a tubular valve body, a downwardly facing annular valve seat around the interior of the valve body defining a first flow passage, a poppet adapted in a closed position to engage said seat from the lower side thereof and close said passage, means mounting said poppet for movement axially of said valve body between said closed position and open positions wherein said poppet is out of engagement with said seat, resilient means urging said poppet against said seat, said poppet having a second flow passage therethrough, an upwardly facing seat around the second flow passage, and a closure engageable with said upwardly facing seat from the upper side thereof, said upwardly facing seat and said closure forming an upwardly opening check valve controlling flow through said fluid passage through said poppet, said poppet and said downwardly facing seat and said resilient means providing a downwardly opening spring loaded poppet valve controlling fluid flow through said first passage, means around the inner periphery of the valve body below said seat providing an annular seal surface of smaller diameter than said inner periphery of the valve body, and a tubular skirt depending from said poppet and extending to said seal surface when said poppet is in sealing engagement with said seat, and slidable therein in sealing engagement therewith when said poppet moves down away from said seat, the outer periphery of said skirt being spaced radially inwardly from said inner periphery of the valve body leaving an annular space therebetween providing a third fluid passage communicating with said first fluid passage when the poppet is off its said seat, port means in said skirt communicating the fluid passage provided by said annular space with a fourth fluid passage defined by the interior of said tubular skirt, said port means being fully open in all positions of said poppet, and an annular flange carried by said skirt andmaking sliding sealing engagement with the inner periphery of said body in said annular space, said flange having an outer diameter greater than that of the outer periphery of the area of contact between said poppet and said downwardly facing seat.

8. Assembly according to claim 7 including port means in said valve body communicating said annular space below said flange with the exterior of said valve body.

9. Assembly according to claim 7 wherein said resilient means is a helical spring disposed in said annular space and bearing at one end against said flange and at the other end against said means around the inner periphery of the valve body below said seal providing an annular seal surface of smaller diameter than said inner periphery.

10. Assembly according to claim 9 wherein said body has a threaded box at the lower end thereof and the last said means comprises a double pin sub having one pin screwed into said box, the last said pin carrying an annular lip seal interiorly near the end thereof, the other pin extending away from said box and providing means for making connection with another threaded box.

11. Assembly according to claim 10 wherein said valve body has a threaded box at its upper end and said annular valve seat comprises a sub pin screwed into said box and having an annular conical downwardly flaring surface at its lower end.

12. Assembly according to claim 7, said check valve closure also having a tubular skirt depending therefrom extending telescopically within the first said tubular skirt, and port means in the second said tubular skirt providing for fluid flow through said second flow passage when said check valvev is .open.

13. Assembly according to claim 12, said tubular skirts being provided with interengageable means limiting upward telescopic motion of the second said skirt relative to the first said skirt, thereby limiting upward travel of said check valve closure away from said upwardly facin seat.

14.Assem ly according to claim 13, sald check valve closure when away from said upwardly facing seat in the poppet to the limit of upward travel of said check valve closure being out of contact and uncooperative with any other means to limit flow through said assembly, said check valve closure including a central frangible portion, the space in said assembly inside said tubular valve body above said closure being clear of obstructions to the passage of tools, whereby upon breaking out of said frangible portion of said check valve closure there is left a clear path for tools through said flow passage through said poppet.

15. A kelly foot valve assembly comprising a tubular valve body, a downwardly facing annular valve seat around the interior of the valve body defining a first flow passage, a poppet adapted to engage said seat from the lower side thereof and close said passage, resilient means urging said poppet against said seat, said poppet having a second flow passage therethrough, an upwardly facing seat around the second flow passage, and a closure engageable with said upwardly facing seat from the upper side thereof, said upwardly facing seat and said closureforming an upwardly opening check valve controlling flow through said fluid passage through said poppet, said poppet and said downwardly facing seat and said resilient means providing a downwardly opening spring loaded poppet valve controlling flow through said first passage, means around the inner periphery of the valve body below said seat providing an annular seal surface of smaller diameter than said inner periphery of the valve body, a tubular skirt depending from said poppet and extending to said seal surface when said support is in sealing engagement with said seat, and slidable therein in sealing engagement when said poppet moves down away from said seat, the outer periphery of said skirt being spaced radially inwardly from said inner periphery of the valve body leaving an annular space therebetween providing a third fluid passage communicating with said first fluid passage when the poppet is off its seat, port means in said skirt communicating the fluid passage provided by said annular space with a fourth fluid passage defined by the interior of said tubular skirt, and foraminous means over said port means providing a strainer for fluid flowing through said assembly.

16. Assembly according to claimlS wherein said foraminous means comprises a perforate steel sleeve secured to said skirt over said port means.

i III li i 

1. A kelly foot valve assembly comprising a tubular valve body, a downwardly facing annular valve seat around the interior of the valve body defining a first flow passage, a poppet adapted to engage said seat from the lower side thereof and close said passage, resilient means urging said poppet against said seat, said poppet having a second flow passage therethrough, an upwardly facing seat around the second flow passage, and a closure engageable with said upwardly facing seat and said closure forming an upwardly opening check valve controlling flow through said fluid passage through said poppet, said poppet and said downwardly facing seat and said resilient means providing a downwardly opening spring loaded poppet valve controlling fluid flow through said first passage, means limiting the upward travel of said check valve closure away from said upwardly facing seat, said check valve closure when away from said upwardly facing seat in the poppet to the limit of upward travel of said check valve closure being out of contact and uncooperative with any other means to limit flow through said assembly, said closure including a central portion that is frangible, the space in said assembly inside said tubular valve body above said closure being clear of obstructions to the passage of tools, whereby a bar can be lowered from above into contact with said central portion to break it out and upon breaking out of said central portion of the closure there is left a clear path for tools through said flow passage through said poppet, said closure including a steel ring into which is screwed a frangible member adapted to be replaced when broken out, said frangible member being cone shaped, flaring downwardly, whereby the strength of said cone is increased with respect to resistance to fluid pressure from above allowing the frangible member to be made of thin material to facilitate breakout, and whereby fluid flow past said closure when said poppet is open is less turbulent.
 2. Assembly according to claim 1 wherein said frangible member comprises a thin laminate including an inner core of brittle aluminum.
 3. A kelly foot valve assembly comprising a tubular valve body, a downwardly facing annular valve seat around the interior of the valve body defining a first flow passage, a poppet adapted to engage said seat from the lower side thereof and close said passage, resilient means urging said poppet against said seat, said poppet having a second flow passage therethrough, an upwardly facing seat around the second flow passage, and a closure engageable with said upwardly facing seat from the upper side thereof, said upwardly facing seat and said closure forming an upwardly opening check valve controlling flow through said fluid passage through said poppet, said poppet and said downwardly facing seat and said resilient means providing a downwardly opening spring loaded poppet valve controlling fluid flow through said first passage, and means limiting the upward travel of said check valve closure away from said upwardly facing seat, said check valve closure when away from said upwardly facing seat in the poppet to the limit of upward travel of said check valve closure being out of contact and uncooperative with any other means to limit flow through said assembly, said closure including a central portion that is frangible, the space in said assembly inside said tubular valve body above said closure being clear of obstructions to the passage of tools, whereby a bar can be lowered from above into contact with said central portion to break it out and upon breaking out of said central portion of the closure there is left a clear path for tools through said flow passage through said poppet, including means around the inner periphery of the valve body below said seat providing an annular seal surface of smaller diameter than said inner periphery of the valve body, and a tubular skirt depending from said poppet and extending to said seal surface when said poppet is in sealing engagement with said seat, and slidable therein in sealing engagement therewith when said poppet moves down away from said seat, the outer periphery of said skirt being spaced radially inwardly from said inner periphery of the valve body leaving an annular space therebetween providing a third fluid passage communicating with said first fluid passage when the poppet is off its said seat, and port means in said skirt communicating the fluid passage provided by said annular space with a fourth fluid passage defined by the interior of said tubular skirt, the inner diameter of said tubular skirt being as large as the outer diameter of said frangible central portion of the check valve closure whereby all tools that will pass through the remainder of said check valve after said central portion is broken out can pass downwardly through said fourth passage.
 4. A kelly foot valve assembly comprising a tubular valve body, a downwardly facing annular valve seat around the interior of the valve body defining a first flow passage, a poppet adapted to engage said seat from the lower side thereof and close said passage, resilient means urging said poppet against said seat, said poppet having a second flow passage therethrough, an upwardly facing seat around the second flow passage, and a closure engageable with said upwardly facing seat from the upper side Thereof, said upwardly facing seat and said closure forming an upwardly opening check valve controlling flow through said fluid passage through said poppet, said poppet and said downwardly facing seat and said resilient means providing a downwardly opening spring loaded poppet valve controlling fluid flow through said first passage, said closure including a steel ring into which is screwed a frangible member adapted to be replaced when broken out, said frangible member comprising an inner core of brittle aluminum and an outer layer of rubber carrying threads for engagement with said closure.
 5. Assembly according to claim 4 wherein said frangible member also includes a rubber inner layer.
 6. Assembly according to claim 5 wherein said closure is cone shaped, flaring downwardly.
 7. A kelly foot valve assembly comprising a tubular valve body, a downwardly facing annular valve seat around the interior of the valve body defining a first flow passage, a poppet adapted in a closed position to engage said seat from the lower side thereof and close said passage, means mounting said poppet for movement axially of said valve body between said closed position and open positions wherein said poppet is out of engagement with said seat, resilient means urging said poppet against said seat, said poppet having a second flow passage therethrough, an upwardly facing seat around the second flow passage, and a closure engageable with said upwardly facing seat from the upper side thereof, said upwardly facing seat and said closure forming an upwardly opening check valve controlling flow through said fluid passage through said poppet, said poppet and said downwardly facing seat and said resilient means providing a downwardly opening spring loaded poppet valve controlling fluid flow through said first passage, means around the inner periphery of the valve body below said seat providing an annular seal surface of smaller diameter than said inner periphery of the valve body, and a tubular skirt depending from said poppet and extending to said seal surface when said poppet is in sealing engagement with said seat, and slidable therein in sealing engagement therewith when said poppet moves down away from said seat, the outer periphery of said skirt being spaced radially inwardly from said inner periphery of the valve body leaving an annular space therebetween providing a third fluid passage communicating with said first fluid passage when the poppet is off its said seat, port means in said skirt communicating the fluid passage provided by said annular space with a fourth fluid passage defined by the interior of said tubular skirt, said port means being fully open in all positions of said poppet, and an annular flange carried by said skirt and making sliding sealing engagement with the inner periphery of said body in said annular space, said flange having an outer diameter greater than that of the outer periphery of the area of contact between said poppet and said downwardly facing seat.
 8. Assembly according to claim 7 including port means in said valve body communicating said annular space below said flange with the exterior of said valve body.
 9. Assembly according to claim 7 wherein said resilient means is a helical spring disposed in said annular space and bearing at one end against said flange and at the other end against said means around the inner periphery of the valve body below said seal providing an annular seal surface of smaller diameter than said inner periphery.
 10. Assembly according to claim 9 wherein said body has a threaded box at the lower end thereof and the last said means comprises a double pin sub having one pin screwed into said box, the last said pin carrying an annular lip seal interiorly near the end thereof, the other pin extending away from said box and providing means for making connection with another threaded box.
 11. Assembly according to claim 10 wherein said valve body has a threaded box at its upper end and said annular valve seat comprises a sub pin screwed into saiD box and having an annular conical downwardly flaring surface at its lower end.
 12. Assembly according to claim 7, said check valve closure also having a tubular skirt depending therefrom extending telescopically within the first said tubular skirt, and port means in the second said tubular skirt providing for fluid flow through said second flow passage when said check valve is open.
 13. Assembly according to claim 12, said tubular skirts being provided with interengageable means limiting upward telescopic motion of the second said skirt relative to the first said skirt, thereby limiting upward travel of said check valve closure away from said upwardly facing seat.
 14. Assembly according to claim 13, said check valve closure when away from said upwardly facing seat in the poppet to the limit of upward travel of said check valve closure being out of contact and uncooperative with any other means to limit flow through said assembly, said check valve closure including a central frangible portion, the space in said assembly inside said tubular valve body above said closure being clear of obstructions to the passage of tools, whereby upon breaking out of said frangible portion of said check valve closure there is left a clear path for tools through said flow passage through said poppet.
 15. A kelly foot valve assembly comprising a tubular valve body, a downwardly facing annular valve seat around the interior of the valve body defining a first flow passage, a poppet adapted to engage said seat from the lower side thereof and close said passage, resilient means urging said poppet against said seat, said poppet having a second flow passage therethrough, an upwardly facing seat around the second flow passage, and a closure engageable with said upwardly facing seat from the upper side thereof, said upwardly facing seat and said closure forming an upwardly opening check valve controlling flow through said fluid passage through said poppet, said poppet and said downwardly facing seat and said resilient means providing a downwardly opening spring loaded poppet valve controlling flow through said first passage, means around the inner periphery of the valve body below said seat providing an annular seal surface of smaller diameter than said inner periphery of the valve body, a tubular skirt depending from said poppet and extending to said seal surface when said support is in sealing engagement with said seat, and slidable therein in sealing engagement when said poppet moves down away from said seat, the outer periphery of said skirt being spaced radially inwardly from said inner periphery of the valve body leaving an annular space therebetween providing a third fluid passage communicating with said first fluid passage when the poppet is off its seat, port means in said skirt communicating the fluid passage provided by said annular space with a fourth fluid passage defined by the interior of said tubular skirt, and foraminous means over said port means providing a strainer for fluid flowing through said assembly.
 16. Assembly according to claim 15 wherein said foraminous means comprises a perforate steel sleeve secured to said skirt over said port means. 